Automatic CNC machine tools, known as machining centers or as machine tool centers, are used to machine various materials. A rotating cutting tool ordinarily accomplishes the machining. The cutting tool is held in a spindle and rotated. Moving the cutting tool through the material under pre-programmed control allows for precise and complex machining to be accomplished. The machining operation, also may include the use of different tools which the machining center may be programmed to select from a magazine of the machining center, and mount it sequentially in the spindle. The tools used by the machining center may be of various lengths and configurations.
The cutting operation by the machining center may produce excess heat by the action of the cutting tool against the material. This heat adversely influences the cutting tool and/or the material being machined. Application of a stream of fluid coolant to the interface of the tool and the material where the cutting action is occurring must be employed to extend the life of the cutting tool and retain the properties of the material. The coolant fluid may be of a liquid or gaseous form. Current practice involves positioning static or manually adjusted nozzles mounted to the head of the machining center. This practice is problematic due to the fact that tools of various lengths are used throughout the machining process, and a stationary nozzle can only project coolant at one point on the extended centerline of the cutting tool. Operator intervention to manually adjust the nozzle might involve interrupting the operation, slowing the process, and subjecting the operator to a hazardous environment.
One known improvement to manual adjustment of the coolant nozzle is described in U.S. Pat. No. 5,444,634. This patent is directed to a nozzle that is mounted in a housing or the like that can be controlled to move in a manner commensurate with the programmed movement of a particular tool in the spindle. The nozzle is programmed by a xe2x80x9cteachxe2x80x9d mode that follows step-wise xe2x80x9cjogxe2x80x9d movements of the tool prior to actual machining of a work piece. The patent does not describe how the nozzle program keeps track of the changing tools, especially in an arm-type automatic tool changer. Furthermore, the nozzle described in this patent is not suitable for handling high-pressure discharge of coolant, nor is it readily adaptable as a back-fit for upgrading existing machining centers.
The present invention is directed to a remotely controlled coolant nozzle system for mounting to a machine tool center. The nozzle system is mounted to the machine tool such that the coolant stream intersects the tool and work surface interface or a point selected by the operator. The system includes at least one coolant nozzle mounted at right angles to the center axis of a rotating fluid handling manifold block. This allows the nozzle to rotatably direct coolant fluid to the interface of the working tool and the material, as the working tool moves along its perpendicular axis. The manifold block is rotated by electromechanical means (stepping motor or servo actuator) which receives electronic control signals.
The pathway of the coolant fluid is from a coolant fluid source to a coolant fluid input port of a rotating coolant union. The coolant fluid travels through the rotating coolant union to the manifold block. The pathway through the manifold block is coincident with that of the block centerline. The fluid passage through the block extends to a point where it intersects a fluid pathway from the nozzle. The fluid pathway through the nozzle, the nozzle bore, is formed around the centerline axis of the nozzle. Because the nozzle bore is formed around the centerline axis of the nozzle, the nozzle bore intersects the centerline axis of the manifold block around which the fluid pathway is formed, and the manifold block rotates around this center line axis, the torque required for rotating the block, is unaffected by coolant flow or pressure through the fluid pathway and out the nozzle. This allows for the use of a commercially available servo actuator or stepping motor that does not have to withstand high tortional forces and thus achieves high resolution at low cost even when handling great pressures and volumes of cooling fluid. The rotating coolant union allows for the manifold block to be attached to a fixed incoming coolant line and to be rotatable while maintaining a fluid communication with the coolant line. The manifold block rotates around its center axis when acted on by the electromechanical actuator. The actuator and the block may be connected in a variety of ways. A few examples are direct connections, connections utilizing gears, connections using flexible shafts or connections to thrusting and contracting piston assemblies.
The invention also includes a method for controlling a coolant fluid nozzle assembly mounted to the machine tool center. The location of the tool and material interface is determined and signals are sent based on that determination to an electronic control system. The electronic control system processes the sensor signals and then sends control signals to the electromechanical actuator. The electromechanical actuator rotates the manifold block to which the nozzle is connected in response to the control signals. The stream of coolant coming out of the nozzle is thus rotatably directed to the interface in a manner that is commensurate with change in location of the tool along its perpendicular axis.